JP2000017258A - Phosphor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phosphor having a lowered emission initiation voltage and sufficient luminance by incorporating lanthanum in a solid solution in a specified electron-beam-excitable titanate phosphor. SOLUTION: This phosphor is prepared by incorporating lanthanum in the form of a solid solution in an electron-beam-excitable titanate phosphor containing a group 2 element as a constituent and containing a rare earth element as a luminescent center. The amount of the lanthanum present in the from of a solid solution is above 0 mol.% to below 8 mol.% and s desirably in the range of 0.04-4 mol.%. The group 2 element used is Sr or Ca. The rare element used is an element selected from the group consisting of Pr, Eu, and Y. The phosphor may further contain an element selected from the group consisting of Al, Ga, and In being group 3b elements. By adding La, it is possible to lower the emission initiation voltage of e.g. an SrTiO3: Pr or CaTiO3: Pr phosphor containing added Al or Ga and to thereby improve its luminance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor which emits light by the impact of an electron beam and a method for producing the same. In particular, the phosphor of the present invention has a fluorescent display device (Vacuum Fluorescent Diode) in which the driving voltage of the anode on which the phosphor is provided is 1 kV or less.
splay, abbreviated as VFD), a light emitting element (Field Emission Display, abbreviated as FED) using a field emission cathode as a cathode electron source, and a phosphor used as a light emitting portion in an arc tube of a large display device. is there.

[0002]

2. Description of the Related Art At present, the mainstream of red-emitting phosphors in VFD is (Zn, Cd) S: Ag, etc. In recent years, Al-added SrTi as another red phosphor has been recently used.
O ₃ : Pr and the like have also been developed. Further, a phosphor obtained by adding Al or Ga to a group 2 titanate is also disclosed in JP-A-8-85788. This phosphor emits light at a low voltage with an energy gap of 3.3 eV and low matrix resistance.

However, the (Zn, Cd) S: A
Since g phosphor uses Cd, if the phosphor is damaged and leaks to the surrounding environment, an undesirable result may be caused. In addition, since S is contained, if this decomposes and scatters and has an adverse effect on the electron source, a sufficient life may not be obtained.

The luminance of the Al-added SrTiO ₃ : Pr phosphor is as low as 60% as compared with (Zn, Cd) S: Ag, Cl. At a driving voltage of 30 V or less, light emission is reduced by charging, and it is necessary to add a conductive material. However, the addition of the conductive material further lowers the light emission starting voltage and reduces the decrease in luminance. However, since the conductive material is a non-light emitting substance, the light emission luminance is further reduced depending on the amount of addition. . In a VFD for a vehicle, there is a demand for a drive voltage of 15 V or less, but a high luminance is required.
There is a problem that it is difficult to obtain sufficient performance with the TiO ₃ : Pr phosphor.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is intended to reduce the emission start voltage of a SrTiO ₃ : Pr phosphor and to obtain a sufficient emission luminance. It is intended to be.

[0006]

According to a first aspect of the present invention, there is provided a phosphor for exciting a titanate electron beam containing a group 2 element as a constituent and having a rare earth element as an emission center. It is characterized by solid solution.

[0007] The phosphor according to the second aspect is the first aspect.
In the phosphor described, the amount of lanthanum is more than 0 mol%
It is characterized by having a solid solution of less than mol%.

[0008] The phosphor according to the third aspect is the first aspect.
In the phosphor described, the amount of lanthanum to be dissolved is set to 0.1.
It is characterized in that it is set to 04 to 8 mol%.

[0009] The phosphor according to the fourth aspect is the first aspect.
In the phosphor described in the above, the Group 2 element is an element selected from the group consisting of Sr and Ca.

[0010] The phosphor described in claim 5 is a phosphor according to claim 1.
In the phosphor described, Al, Ga, which is a 3b group element,
It is characterized by further containing an element selected from the group consisting of In.

[0011] The phosphor described in claim 6 is the first invention.
The phosphor according to claim 1, wherein the rare earth element is Pr, Y,
It is an element selected from the group consisting of Eu.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present inventors have devoted themselves to the study of SrTiO ₃ : Pr phosphors, which have not always been able to achieve sufficient performance, to lower the light emission starting voltage and obtain sufficient light emission luminance. We have made improvements to make it possible. As a result, the present inventors have obtained the following recognition which is important for the improvement of the phosphor. That is, in order to lower the light emission starting voltage of the phosphor and increase the light emission luminance, it is only necessary to add some substance which is not conventionally known as an additive substance to this kind of phosphor and lower its resistance. The properties required for the additive material include an ionic radius close to the ionic radius of a Group 2 element such as Sr contained as a constituent of the titanate, and 3
It was thought that it had a valence atom. It is considered that if the ionic radius is close, the atoms of the additive substance easily substitute for Sr and have one extra electron than Sr, so that this becomes a donor and contributes to the improvement of conductivity. Because it can be done.

The present inventors have experimentally confirmed the effectiveness of various substances as an additive to the above-described phosphor based on such a novel idea. When La is added, the performance as a phosphor is remarkable. Have found significant improvements. Further research was conducted, and various findings were obtained regarding the production method, the effective amount of addition, and the preferable substances to be added at the same time.

If La is added, for example, Al or Ga
It was found that the light emission characteristics of the added SrTiO ₃ : Pr or CaTiO ₃ : Pr phosphors were improved, such as further lowering the light emission start voltage and improving the luminance.

[0015]

EXAMPLES (1) Example 1 PrCl ₃ 0.2 per 1 mol of SrCO ₃ and TiO ₂
5 mol%, Al (OH) ₃ 20 mol% and La ₂
O ₃ were mixed 0.04~8mol%, in the atmosphere 1100 to
After firing at 1300 ° C., a dispersion treatment was performed to obtain a sample of an Al-added SrTiO ₃ : Pr phosphor having a different La content.

These samples were mounted on a fluorescent display tube and evaluated. The lighting condition is that the anode voltage is 30 V or less. For comparison, a phosphor containing no La was evaluated under the same conditions. FIG. 1 shows the relationship between the added amount of La ₂ O ₃ and the relative luminance value. FIG. 2 shows the relationship between the added amount of La ₂ O ₃ and the life characteristics.

When compared at an anode voltage of 15 V, it was found that a small amount of the initial luminance had a certain effect when added, and conversely, the effect was lost when the added amount was increased to a certain degree or more. In this example, it can be seen that the effect of improving the luminance can be obtained in a range of about 8 mol% or less. The effective range is 4 mol% or less, and the optimal range is between 0.04 and 0.4 mol%. In addition, also in the life characteristics, an effect was recognized when a small amount was added, and particularly, a remarkable effect was recognized at 0.04 mol% or more. No change in chromaticity is observed.

(2) Example 2 A sample was prepared in the same manner as in Example 1 except that Al was changed to Ga.
did. Ga is Ga_TwoO _Three5 mol% addition with Ga
The sample with 0.1% La added and the sample without La
And evaluated similarly.

When the luminance was evaluated at an anode voltage of 15 V, the sample of the present invention was 1 for 100 cd / m ² without addition.
90 cd / m ² was obtained.

(3) Example 3 The group 2 element which is a phosphor constituent element is changed from Sr to Ca,
A CaTiO ₃ : Pr phosphor was produced. CaCO ₃ , T
0.25 mol of PrCl ₃ for each 1 mol of iO ₂
%, Al (OH) ₃ 2 mol% and La ₂ O ₃ 0.4
mol%, and calcined at 1100 to 1300 ° C. in the air, and then subjected to dispersion treatment to add La and Al-added CaTiO 3.
₃ : A Pr phosphor sample was obtained.

As a result of the same evaluation, the sample without La added started to emit light at an anode voltage of 10 V,
It was 0 cd / m ² . On the other hand, the sample of the present invention started emitting light at 5 V, and at 15 V, a luminance of 85 cd / m ² was obtained.

(4) Embodiment 4 According to the above-described embodiments, different phosphors can be manufactured by using various substances instead. For example,
Instead of Al and Ga, In which is a 3b group element may be added. This also provides substantially the same effects as in the embodiments (1) and (2). In place of Pr, rare earth element E
Useful phosphors can be obtained similarly by using u and Y.

FIG. 3 is a diagram showing the relationship between the anode voltage and the emission luminance when the phosphor of each embodiment described above and the conventional phosphor containing no La are mounted on the fluorescent display tube.
As can be seen from this figure, the emission start voltage of the conventional phosphor is about 10 V, whereas the phosphor of the example is 4 to 5
V, which indicates the effect of the addition of La.

[0024]

According to the present invention, lanthanum is dissolved in a phosphor for titanate electron beam excitation containing a group 2 element as a constituent and a rare earth element as a luminescent center, so that the conductivity is improved. As a result, a phosphor that emits light from a low voltage and has good initial and life characteristics was obtained. The phosphor is Cd
Because it is not used, even if it is damaged, it has little effect on the environment. Further, a high-resistance red phosphor (Y ₂ O ₃ : Eu)
Etc.) as a conductive material to improve its properties.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the added amount of La ₂ O ₃ and the relative luminance value in an example of the present invention.

FIG. 2 is a graph showing the relationship between the added amount of La ₂ O ₃ and the life characteristics in the example of the present invention.

FIG. 3 is a diagram showing a relationship between an anode voltage and light emission luminance when mounted on a fluorescent display tube, and is a diagram comparing an embodiment of the present invention with a conventional example.

Claims (6)

[Claims] 1. A phosphor for titanate electron beam excitation containing a Group 2 element as a constituent and having a rare earth element as a luminescent center, wherein lanthanum is dissolved as a solid solution. 2. The amount of lanthanum is more than 0 mol% and 8 mol%.
2. The phosphor according to claim 1, wherein said phosphor is less than a solid solution. 3. The phosphor according to claim 1, wherein lanthanum is solid-dissolved in an amount of 0.04 to 4 mol%. 4. The phosphor according to claim 1, wherein said Group 2 element is an element selected from the group consisting of Sr and Ca. 5. The phosphor according to claim 1, further comprising an element selected from the group consisting of Al, Ga, and In, which is a Group 3b element. 6. The phosphor according to claim 1, wherein said rare earth element is an element selected from the group consisting of Pr, Eu, and Y.